Overview and Types of Colon Polyps

Colon Polyp, Drawing
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A polyp is a term used to describe a growth on the lining of a mucous membrane. The growth may develop on the lining of the digestive tract, mouth, uterus, bladder, nasal passages, or genital area. When a polyp develops in the colon, it is usually benign (non-cancerous) but, in some cases, can develop into a malignancy (cancer).

Colon Polyps Symptoms
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Identifying Colon Polyps

There are different types of colon polyps, each of which has its own characteristics and structure. These and other factors (including size and location) can help us determine if they have the potential to develop into colon cancer.

Colon polyps themselves are quite common, occurring in around half of all adults over 60. They are usually found during a visual examination of the colon. When discovered, the growths can be removed and the tissue sent to the lab for evaluation to assess if any abnormalities are suggestive of a malignancy.

Currently, all adults 50 years and older are advised to have a colorectal screening using one of four techniques:


When describing a polyp, a doctor will use words that we recognize (like flat or raised) and some that we don’t. In their entirety, these physical descriptions help the doctor determine how to deal with a polyp should it need to be removed. They also provide insights into its potential for cancer.

Colon polyps come in two basic shapes:

  • Pedunculated polyps are raised, mushroom-like growths that are attached to the surface of the mucous membrane by a long, thin stalk (peduncle).
  • Sessile polyps sit on the surface of the mucous membrane. They are flat and do not have a stalk.

Pedunculated polyps are easier to spot because they are raised. By contrast, sessile polyps lie flat on the surface and are more likely to become cancerous simply by virtue of being missed.


Beyond their physical appearance, the doctor will want to determine what type of polyp it is. This typically requires examining the tissue under a microscope to look at both the cellular structure and the characteristics of the cells themselves. Among the more common classifications:

  • Inflammatory colon polyps are mostly found in people with an inflammatory bowel disease (IBD), such as Crohn’s disease or ulcerative colitis. Inflammatory polyps are sometimes referred to as "false polyps" because these aren’t polyps per se but rather an inflammatory manifestation of IBD. These polyps are benign and are unlikely to become cancer.
  • Hyperplastic polyps are defined by the activity of cells in the tissue mass. Hyperplasia ("fast growth") simply means that there is an abnormal increase in the numbers of cells resulting in the gross enlargement of a polyp. Despite the rapid growth, hyperplastic polyps are considered to be at low risk of turning cancerous. (An enlarged prostate is another example of benign hyperplasia.)
  • Adenomatous polyps, or adenomas, make up about 70 percent of all polyps found in the colon. While adenomas can become cancerous, the process can typically take years. As opposed to hyperplastic polyps, adenomas are neoplastic. Neoplasia ("new growth") is a term used to describe an abnormal growth of cells that gradually lose the characteristics of normal cells. When neoplastic cells form into a mass, we refer to that as a tumor. A neoplasm can be benign, malignant, or something in between.
  • Villous adenoma is a type of adenomatous polyp that has a greater potential of becoming cancerous. It is estimated that around 30 percent of villous adenoma will develop into a malignancy. These polyps often have cauliflower-like protrusions and may require surgery to remove.

Irrespective of the type, any polyp larger than one centimeter should be removed either with a wire loop known as a LEEP or an electrocautery device that burns the polyp at its base.


For the most part, you probably won’t know if you have polyps. You don’t generally can’t feel them, and they are usually only found during a colorectal screen. If symptoms do appear, they may include:

  • Changes in bowel habit, including constipation or diarrhea
  • Blood in stools (either dark, tarry stools or bright red stools)
  • Abdominal pain

If this combination of symptoms persists for more than a week, make an appointment to see your doctor.

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